Redness with small clear bump on testicals

I shave my testicals probably once or twice a week since I was 17 Im 26 now. Ive been tested for STDs and everything came back negitive but its been about a week now when I shaved I either cut my self on my left testical or just simple broke out with a rash. Its red with small clear bumps from like 3-5 I scratched them causing it to look cut. I have been masterbating so I think thats how all this started. Ive also been trying rash creams in that area but it looks like its speading about half an inch from the spot it all started from. Any one know what this might be?