Severe bloating/pressure lower stomach 3dpo ?

So I'm not 100% sure the exact day I ovulated, I haven't been tracking the last few months but I was tracking for 4 years and it landed within a day or two of the predicted date (so fairly accurate I think).

With that being said, last night and all today I've had a very uncomfortable pressure/severe bloating feeling in my lower abdomen. Like way low, below the belt line and center. I've also been nauseous off and on. It's really uncomfortable and I can feel it when I walk especially.

Any ideas what this could be? Has anyone else on here experienced this?