back shoulder has dryish round red rash , does not itch but has gotten larger in past week
It may or may not be spider bite, reaction from the toxic bugs are also same like, redness, pain, swelling or itching.
if the redness is spreading away from the bite, as you said then consult your doctor before it gets worse.
also check below remedies
as some of the spiders are poisonous so better consult your doctor ASAP.
if it is similar to a bullseye rash out could be an indication of lyme disease and you need to have a blood test done immediately since lyme is harder to treat after so long of having it.most times you won’t even feel the rock and sometimes the rash occurs in a different spot and from what I hear they usually don’t itch and some o’toole dont get the bullseye rash but just a round rash.