FERTILE CM 3/4 DPO?

I just had A LOT of EWCM come out and it's 3/4 DPO. I had a positive OPK (3/4 days ago). And I'm cramping and bloated and trouble emptying bladder. I'm on antibiotics too but have been for a week already. I cramp during O but I've been cramping the last couple days. 
Is this a sign of implantation or late O?