Is it red with a red ring around it?
It might be Lyme Disease. The center of the ring is where the tick bit, and the ring indicates that the tick may have given you Lyme Disease. Lyme Disease is a viral illness that causes fatigue, headaches, and fever, but the rash is the most clear sign (short of a blood test, although those can be wrong too!).
See a doctor if you suspect Lyme Disease ASAP. It’s only serious if you don’t get it treated.
Painful Blisters Around Your Torso?
It might be a shingles rash. Shingles rashes are a painful, recurrent form of chickenpox that’s triggered when you’re under stress, or your immune system is weak (age is a big cause, but other illnesses can do it).
Don’t scratch, and other than that, just wait it out. That means typical viral treatment: rest, fluids, and maybe a good cup of tea.
A Growing Red Or Tan Spot That Itches?
If it’s on your groin or feet, it’s probably Athlete’s Foot/Jock Itch. Your skin hosts all kinds of bacteria, viruses, and fungi. But if you work out a lot, it could cause a buildup of moisture and dead skin cells that helps some of that yeast to thrive and cause a skin infection. Dry it out, exfoliate, and if symptoms get worse, see a doctor.
What skin issues are you curious about?