Stomach and back pain

I had a miscarriage in July. I got pregnant again and I’m currently 8 weeks. I saw the baby at 6 weeks 5 days with a beating heart. Everything is going fine. I haven’t had too many symptoms but today I have this feeling I really need to use the restroom but I can’t. I’ve had mild diarrhea and now it seems like constipation. I have so much gas as well, but it doesn’t leave my body. I’m also having mild lower back pain. None of this is debilitating but super super uncomfortable. The gas makes my stomach huge, as if I’ve eaten ten dinners and I’ve hardly eaten today. I also get out of breathe just from standing up. Is this normal? Hopefully you understand why I’d worry about something like this given my past experience.