My belly is sore this morning

Mimi β€’ I'm 18 years young πŸ’πŸΎπŸ‘‘, I go by Mimi πŸ˜‹, I found out I was pregnant 5/15/17 πŸ€°πŸΎπŸ’•!
I just woke up like 5 minutes ago and my belly is sore this morning why? (19 weeks and 4 days)