Intense Back Pain

I have had a mild back ache here and there as we all do during pregnancy. I haven't had one for the past couple of days and I haven't done anything strenuous but today, it's a very intense constant pain. It's my lower and mid back. I've been having Braxton hicks but nothing more than 1 or 2 an hour. Would you call your doctor? It's been happening for about 6 hours. Thanks!