An extensive list of 240 symptoms for your bespoke plagues, curses, and afflictions. Roll a d12 and a d20 together and treat each as a digit instead of adding them together.
(Note: I always encourage folks to look up terms they're not familiar with, but for this be careful. If you search the ones that are real medical conditions you'll find pictures of the most extreme and absolute worst-case examples.)
1.1 Fever
1.2 Hypothermia
1.3 Headache
1.4 Dizziness
1.5 Fatigue
1.6 Fainting
1.7 Chills
1.8 Shivering
1.9 Sweating
1.10 Shock
1.11 Coma
1.12 Body aches
1.13 Swollen lymph nodes
1.14 Dehydration
1.15 Thirst
1.16 Hunger
1.17 Loss of appetite
1.18 Malnutrition
1.19 Emaciation
1.20 Weight gain
2.1 Weight loss
2.2 Elevated heart rate
2.3 Lowered heart rate
2.4 Arrhythmia
2.5 Avolition
2.6 Apathy
2.7 Anxiety
2.8 Paranoia
2.9 Confusion
2.10 Mood swings
2.11 Impulsiveness
2.12 Irritability
2.13 Rage
2.14 Hysterical strength
2.15 Uncontrollable laughter
2.16 Delirium
2.17 Delusions
2.18 Amnesia (short-term)
2.19 Amnesia (long-term)
2.20 Disorientation
3.1 Stupor
3.2 Unresponsiveness
3.3 Ahedonia
3.4 Aphasia
3.5 Echolalia
3.6 Faceblindness
3.7 Desire to sleep (somnolence)
3.8 Insomnia
3.9 Nightmares
3.10 Sleepwalking
3.11 Vertigo
3.12 Hallucinations (auditory)
3.13 Hallucinations (visual)
3.14 Hallucinations (olfactory)
3.15 Hallucinations (taste)
3.16 Hallucinations (touch)
3.17 Phantom pain
3.18 Slurred speech
3.19 Formication
3.20 Loss of proprioception
4.1 Loss of smell (anosmia)
4.2 Loss of taste (ageusia)
4.3 Synesthesia
4.4 Hypersensitivity
4.5 Hypoalgesia
4.6 Numbness
4.7 No reflex response
4.8 Tremor
4.9 Convulsions
4.10 Seizure
4.11 Paralysis
4.12 Hypertonia
4.13 Arthritis
4.14 Joint pain
4.15 Hypermobility
4.16 Ankylosis
4.17 Joints fuse
4.18 Extra joints
4.19 Brittle bones
4.20 Hyper-dense bones
5.1 Bones lengthen
5.2 Bones soften
5.3 Bones dissolve
5.4 Atrophy
5.5 Muscle weakness
5.6 Muscular hypertrophy
5.7 Tumors
5.8 Inflammation
5.9 Ulceration
5.10 Necrotic tissue
5.11 Gangrene
5.12 Hair loss
5.13 Hair growth (fast)
5.14 Hair growth (abnormal)
5.15 Dry hair
5.16 Split ends
5.17 Nail discoloration
5.18 Nails thicken
5.19 Weak nails
5.20 Nails fall out
6.1 Itching
6.2 Dry skin
6.3 Cracked skin
6.4 Peeling skin
6.5 Blistering
6.6 Rash (red speckles)
6.7 Rash (ring-shaped)
6.8 Rash (pale white spots)
6.9 Rash (oval blue spots)
6.10 Rash (black threadlike strands)
6.11 Rash (fractal)
6.12 Hives
6.13 Pox sores
6.14 Necrotic sores
6.15 Weeping sores
6.16 Bubos
6.17 Warts
6.18 Bruising
6.19 Skin discoloration
6.20 Jaundice
7.1 Cyanosis
7.2 Pallor
7.3 Veins visible through skin
7.4 Skin turns transparent
7.5 Itchy eyes
7.6 Red eyes
7.7 Bloodshot eyes
7.8 Bleeding eyes
7.9 Inky black tears
7.10 Cataracts
7.11 Blindness
7.12 Color blindness
7.13 Light sensitivity
7.14 No pupilary light reflex
7.15 Pupil shape changes (rectangle)
7.16 Pupil shape changes (star)
7.17 Pupil shape changes (slit)
7.18 Dark ring around the iris
7.19 Gold ring around the iris
7.20 Increased visual spectrum range
8.1 Eyes turn entirely black
8.2 Eyes turn entirely blue
8.3 Glowing eyes
8.4 Extra eyes
8.5 Deafness
8.6 Tinnitus
8.7 Increased hearing frequency range
8.8 Sneezing
8.9 Runny nose
8.10 Postnasal drip
8.11 Blocked sinuses
8.12 Nosebleed
8.13 Bleeding gums
8.14 Pale gums
8.15 Drooling
8.16 Sore throat
8.17 Difficulty swallowing
8.18 Swollen tongue
8.19 Fissured tongue
8.20 Thrush
9.1 Tongue lengthens
9.2 Loss of voice
9.3 Goiter
9.4 Grinding teeth
9.5 Teeth turn gray
9.6 Teeth crack and erode
9.7 Teeth fall out
9.8 Teeth regrow
9.9 Teeth change shape
9.10 Teeth fuse
9.11 Teeth replaced by metal
9.12 Teeth glow
9.13 Cough (dry)
9.14 Cough (productive)
9.15 Cough (bloody)
9.16 Difficulty breathing
9.17 Pneumonia
9.18 Blood won't clot
9.19 Blood congeals
9.20 Blood powders
10.1 Blood turns silver
10.2 Blood turns green
10.3 Blood replaced by milk
10.4 Nausea
10.5 Vomiting
10.6 Heartburn
10.7 Cramps
10.8 Gas
10.9 Burping
10.10 Flatulence
10.11 Constipation
10.12 Diarrhea
10.13 Autobrewery syndrome
10.14 Clear urine
10.15 Dark urine
10.16 Bloody urine
10.17 Sky blue urine
10.18 Anuria
10.19 Excessive urination
10.20 Incontinence
11.1 Priapism
11.2 Erectile dysfunction
11.3 Infertility
11.4 Excessive menstruation
11.5 False pregnancy
11.6 No pulse
11.7 Not breathing
11.8 Growth spurt
11.9 Fingers lengthen
11.10 Bifurcating fingers
11.11 Shrinking
11.12 Sweat turns caustic
11.13 Writing appears on skin
11.14 Progressive petrification
11.15 Vomiting toads
11.16 Egg-laying
11.17 Spontaneous bleeding
11.18 Spontaneous ignition
11.19 Spores
11.20 Fruiting bodies
12.1 Hives (insect)
12.2 Budding
12.3 Involuntary bilocation
12.4 Chronic teleportation
12.5 Levitation
12.6 Involuntary ventriloquism
12.7 Can only talk backwards
12.8 Involuntary telepathy
12.9 Telepathy
12.10 Clairaudience
12.11 Clairvoyance
12.12 Immateriality
12.13 Regeneration
12.14 Immortality
12.15 Undeath
12.16 Sunlight sensitivity
12.17 Silver allergy
12.18 Allium allergy
12.19 Autophagia
12.20 Temporal dislocation