Implantation bleeding or period?? TMI

So, Last Thursday I had light pink discharge and then nothing the next day. Then on Saturday I had a rush of blood that lasted all day and filled up 3 tampons. I bled through the night and filled a regular pad and the next day I continued to fill 3 more tampons. I've had about 5 days of bleeding and it's been red in color along with a little bit of brown discharge on the tampon. Do you think that it's my period? ALSO, I didn't have sex. I'm freaking out because my SO fingered me and I gave him a hand job (might have been a small amount of pre-cum but NO ejaculation) and then around 10 minutes later I used the bathroom.  n February I had my period for 8 days and then a week and a half later I had another period!! I had spinal fusion surgery 3 months ago however and I'm thinking my cycle could be thrown off from that. What do you think about this situation? Am I freaking out for no reason?