Hi, yes I agree either see a doc or if not go to a&e asap. I had a miscarriage a couple of weeks back and had these symptons, then a few days ladter had heavy bleeding, went for scan and there was no heart beat, few days later I miscarried naturally. I hope everything works out ok but with you having the cramps aswel I would defo seek medical advice and book a scan in as soon as. I do hope all is well for you though.
you need to make an apt with your dr ASAP. You need to have an exam done and an ultrasound, and (if your RH Negative you need a shot).
When I was 11 weeks I had HORRIBLE back pain and slight spotting (like once a day when I wiped, no panty liner). I had an exam done and everything looked great, but after having an ultrasound found out that i was having a missed miscarriage (It had been about 5 weeks since the baby developed, however I was still growing in size). I end up having a D&C and recovered very well.
I don't mean to scare you, but you really need to see the dr. You may or may not be having a miscarriage, with out an ultrasound you really won't know.
I hope things turn out better for you! I also had a son now 19 months old and it was a "perfect" pregnancy with no issues other than being strep b positive.