My eczema is so bad I can't sleep at night.
I got medicine for my rash from the doctor.
I got a rash on my arm and it's itchy.
I break out in a rash when I use this cosmetic.
The rash got worse after I stopped applying the medicine.
I had my rash treated at a dermatology clinic.
I ended up scratching the rash, which made it even redder.
湿疹 is eczema, a different skin condition, whereas 湿 in its medical sense refers specifically to scabies caused by mites.
湿疹 (eczema) names a specific inflammatory skin condition with its own medical cause, while 吹き出物 is a vague, general term for any visible bump or spot.
肌荒れ is a general, everyday word for skin that looks or feels bad, while 湿疹 is a medical term for a specific inflammatory skin condition (eczema/rash) that a doctor would diagnose.