Clear stretchy CM 4 days before period due...

I'm not positive when I O'd. First month using OPKs and I'm not convinced that I got a positive. I have new sort of dry this month but I just went to the bathroom. I checked and didn't really have any CM then I wiped and had a bunch of clear stretchy CM. I then checked with my finger and a big glob came out. Slightly greenish when on toilet paper. Super super stretchy... I sometimes get a small glob of brownish discharge the day before AF. But I'm not due until Tuesday/Wednesday. Thoughts? I've been cramping for the past 3 days. Very mild cramps and I generally get horrid cramps with AF. Super moody also. Is it just pms?