38 weeks pregnant and abdominal pain when needed a poo!?

i know this sounds really disgusting but on friday (its now sunday).. all of a sudden i had a mive pain in my abdomen an i had 2 bend over but that didn't really help and it felt like i needed a poo.. so the pain lasted about 10-20 secs an i went to the toilet fine.. i thought that was it.. so i ignored this and thought nothing of it.. then the next morning at 10am it came on strong again.. just as strong as the last one and it felt like i needed a poo again so i went.. then all that day i had been getting twinges and can really feel him 'playing' or moving about really in my pelvis and every now and then i get little twinges and my back is really killing and has been for a couple of days its really getting uncomfortable.. could it be braxton hicks or the start of slow labour? please help!