Tummy tightness 4 weeks along

Samantha
Hi ladies, i just recently got my BFP, I'm about 4 weeks along with my second, and one loss in between, I've been noticing a tightness off and on in my stomach which has been happening only at night for a few hours at a time, after 7pm usually. Any ideas on what this might be? It's a new feelings I haven't had this pregnancy symptom before. Thank you all for any insight and best of luck to everyone ❤️