I am randomly breaking out in large red rashes on forearms, they are extremely itchy.?

Looks like some are trying form around my ribs. I havent broke out since I was a child. I'm 25 now. I was outside doing some yard work 2-3 weeks ago. Some bumps appeared afterwards but vanished in a few days. What could this be from? Any remedies I can buy or make? Seeing a doctor is not a option. And here I thought I was over ever breaking out and I randomly break out on my 25th birthday. Hmmmm. I'm not allergic to anything. 25 years strong with doing whatever I want but now I randomly break out in hives.