Possible ectopic?

I'm scared that I may be having an ectopic. I don't feel like my usual self tonight. Earlier in the week I assumed that I had a chemical pregnancy when tests became negative and my beta was at a 7, and then I got my period. Well tonight I started having sharp pains in my right side, and I feel very weak and tired. I would have been 5 weeks tomorrow. I don't want to have to go to the ER for nothing. What do you guys think? I checked an hpt and it's still negative. The pain is also in my lower back. I'm thinking about just going to sleep if I can and see how I feel in the morning. Has anyone gone through an ectopic here who can shed some light on your symptoms? Thanks!