I freaked out cause I never spotted before!

My period was April 30-4 had unprotected sex 12.13 and 14..I did an ovulation calculator and supposedly the 14 was my ovulation and fertile around that time..May 30 I had brown discharge..no blood so I took it as a start of my normal period but i bleed only two day like a normal period but had cramps the whole time..my period always last 5 days..that Sunday I had really bad cramps to the point wanted to go to hospital but i decided to sleep it off and spotted and I freaked out cause I never spotted before nor felt that kind of cramping..so Monday I took a test and came out negative..so Thursday I decided to go to clinic and came out neg. as well..I'm so confused because I've been having quit a bit of symptoms such as using the bathroom more feeling tired very quick stingy pain in back and breast also headachs..if I were pregnant I would b 6 weeks today but idk if I should wait til next expected period comes and see how that goes or what to do..??
Any advice