Sore Throat, Migraine, Rashes Like Hives On Inner Thighs. Reason?

What could a sore throat, a migraine and rashes on the inner thighs mean? The rashes consist of tiny hives and are not itching or burning in any way. I noticed them when I got dressed this morning. I am thin, so it cannot be from chafing. I am a redhead and spent time in the sun a few days ago for the first day of summer, but i vacation often in hot climates & spend time outside often & this had never happened. i have no allergies, am on no medications, have not changed my detergent, used a different lotion than usual or worn new clothes or clothes that belonged to someone else

I wouldn't think much of it if I wasn't feeling light headed & experiencing the onset of cold symptoms. Thanks in advance.