Im having very painfull braxton hicks?

theres no pattern in-between the pains but theyre lasting about 2-3 mins every time and are getting very painfull. ive been using a birthing ball, only since today but it hurts when i use it. do you think labour could be starting?? as i dont know wether to ring the midwife or not. i havent had a show but saying that, i didnt have a show on my other two pregnancies either..not until just before i had to push anyway. could i be in labour?