could I be pregnant?

Cady

I'm on the nexplanon and my doctor prescribed me topamax for migraines. it says on the bottle it can affect hormonal birth control so I asked my doctor and she said "ehhh you should be fine"....fast forward 2 weeks and I'm having constant nausea, back pain, I have to pee every 5 minutes and my nipples are sore and sensitive. I took a test and it came back very faint but there positive. I don't know what to do. Test again ? it's been 4 days.