Braxton hicks,cramps, backache and constipation (21 weeks)?

I'm 21 weeks and this is my first pregnancy so everything freaks me out. I have been constipated with VERY little relief for about a week now so im sure that's what the backaches and cramps are from. Does constipation cause more frequent braxton hicks? I am not really worried at this point as i'm only having about 2 or 3 an hour and they seem to be going away since I chugged 3 glasses of water and sat down. The backache isn't going away. I plan on taking some colace tonight and If I still feel uncomfortable in the morning I will call but until then, I would love some opinions!