Im having bad cramps in my abdominal area what could it be?

Its been 3 days since i was spotting but now i stopped and the cramps continue my lower abdomen and back hurt, my shoulders feel numb, been having headaches and nausea on and off, very sore breasts. Could it be pms or implantation i can't tell with my irregular periods 😭 i haven't had a period in 4 months