So i've been nauseous, low backaches & having the feeling of diarrhea while my stomach gets tense (not having any, just the stomach feeling that it does)

Is this normal or am I just overthinking? I didn't feel this with my first and idk it got me worried 😬 Also cause the doctor asks specifically about nausea in the third trimester at every appt i've been to and i thought it was normal! TIA 💗