Ectopic pregnancy or random period????

Hey you guys I have a mild concern and no one to really talk to... I started nexplanon in November of 2022. Prior to that I hadn't had a period since my post partum period in 2020. Here it is 2024, still no period and I still have my implant. Here's where it gets weird. About a week and a half ago I started cramping, but I didnt really think much of it because I wasnt bleeding. Boyfriend and I had sex (yes I was also on antibiotics for an ear infection at the time, dumb on my part I know) HOWEVER sunday I took a test and it was negative, I'm still cramping at this point but not bleeding, and my nipples are VERY sensitive... Two days ago I went to the bathroom and noticed I was spotting but it was brown, weird because again.. no period since 2020.. I looked up everything possible and everything I found said the brown was either old blood or implantation bleeding. So I took a test that night and it still came back negative. I'm still cramping horribly, the brown spotting stopped however this morning I went pee and there was a bright red bit of blood and discharge but it was a one time show up thing theres no active flow but I'm still cramping and its isolated to my right side... do I need to take another test or just go to the ER at this point ?