I am getting red sores that look like bug bites on my lower back and now it it spreading.?

The thing is, my mom bought a hot tub a couple of months ago and I have only been in it about 4 or 5 times, last time being last Sunday. About 2 weeks ago, my mom got these same bumps on her stomach around her waistline and thought it was shingles. i thought it might have something to do with the hot tub but she was getting in it every night. Anyway, she took Benedryl and it went away. Now I am getting it on my legs and hips. We haven't been using any different laundry detergent and people say it might be bed bugs but this has never happened to me before except when I had chicken pox as a child and I got them all over me not just in certain spots. I was wondering if anyone out there may have a hot tub that this has happened to before. By the way, the temp. is set on 102-104 F and we only stay in it for 30 minutes and I do take a shower when I get out.