4-5 weeks

Hey everyone. I found out on November 16 I was about 4-5 weeks pregnant he gave me a due date of July 21st which would make me 5w 4 days but told me that would likely change at my next appointment when we could see better. On Sunday the 20th I started having spotting. It ranges with light then gets a little heavier and will stop again. It has been brown, reddish, and pink. Nothing like a period but I'm also experiencing mild cramps but not constantly. My test lines are not as dark as they were. I had a blood test done yesterday and beta was at an 81 I have second one scheduled for Thursday. Has anyone else experienced this?