Unfortunately, they're not in a rush to scan unless the pain is bad. I was told I had high chance of ectopic and would find it difficult to get pregnant before my first because of scarring from an infection (turns out I am extremely fertile!). About six weeks I had low one sided pain, quite bad, and they took me in, couldn't see the baby and operated, removing 'something' from my tube but the baby, now ds, survived the op and was fine, he was just too small to see. No problems with dd, but in this pregnancy, around six/seven weeks, I had low one sided cramping, obviously was worried about ectopic again and the doctor phoned the hospital and they said, next appointment for a scan was in a week, come in then unless the pain got bad or I felt dizzy or started bleeding etc. It was fine again this time (23 weeks now) but I was pretty shocked, I had been expecting to be scanned straightaway like the last time but they seemed pretty relaxed about it. I think the pain might have been the scar tissue, which it could be to do with your ties as well, but don't hesitate to ring them back if you think it's worsening. I couldn't actually stand up straight the first time, although it wasn't ectopic, they never said what they removed, and I know a friend who had one and had to be lifted off the loo. Be vigilant, and keep in contact with them, but I'm not sure it would be that early anyway, commonest time 8/9weeks I think, they probably couldn't see it on a scan at 4 weeks anyway. Incidently, my mother got pregnant with my youngest brother about three years after having the ties. He was a c section and they said they didn't know how it had happened as the ties were still in place, and that she had more chance of winning the lottery! I think now the odds of it happening are higher, or they thought it was more foolproof then.
I really hope you feel better and everything works out for you. I think you'll know if it moves from cramping to real pain, but, remember you're entitled to keep ringing them if you're worried. Good luck!