Is there anyone else who is having a terrible back ache?

From tomorrow I'll be 28 weeks, I've been having a terrible upper back ache on my left side. This started last week after having a long walk up hill because of my part time work, a "Home Based Care" kind of work. Yesterday I ask my husband to massage the aching area and he discovered that I was swollen. What can I use to relieve the pain because is hard to stand, sit or walk? Must I see my doctor or wait because I have a routine check up 5 days from now? Please help