Should I be worried?

I’ve had two miscarriages back to back the most recent one on May 21st. I found out I was pregnant 3 days ago and got the positive blood test results yesterday. It’s showing I’m around 3-4 weeks. I’ve started taking my prenatal medicine yesterday and have been extremely careful with not lifting or over working myself. 
But the past week or so (before I found out I was pregnant) I’ve been having constant back aches (I’ve been told it could be because of the line of work I’m in. I’m an RA and I’m always lifting and bending and straining my back) and I have these freuquent pains in my lower abdomen (feels like a needle poking my skin). My nurse tells me it’s perfectly normal in early pregnancy but because I’m extremely high risk during my pregnancy (due to many of my health problems and the miscarriages I’ve had in the past) I’m terrified it’s not normal and that I’m going to have another miscarriage. Have any of you ladies experienced the same aches and pains I’m describing? Is it normal in the early stages of pregnancy? 
I go to the doctor next Wednesday but I’m terrified to do anything or move to much because of me being high risk and not having a successful pregnancy yet.