Why am I producing milk?!

I don’t know where else to post this I’m sorry if there’s a better place. I’m not pregnant that I know of but I’m starting to freak out!! I’ve been feeling really nauseous on and off now my boobs are so sore and I’ve had weird cramping but not in a few days my bf squeezed my boob and milk came out! I haven’t breastfed in almost 4 months and I checked to make sure I had no more milk left nothing came out of either boob and I only breastfed for two weeks so I didn’t do it very long at all anyway my period is due in 2 days but I literally have no cramps anymore I don’t feel anything. I tested negative with those cheapie strip tests but I guess it may just be too early for a positive or the test isn’t sensitive enough? Has anyone had this happen before and been alright? I’m so anxious right now we just had our baby 4 months ago on the 11th! Ugh please help.