I'm getting pain in my upper back but some cramp in my tummy, my tummy is tightening every 20-30 minutes with hardly any pain, when I called the midwife she says until the pain is unbearable then call back, is this the start of my labour I also lost my mucus plug 3days ago and today I have been very moody, my thighs are achy as well has anybody else experienced this just before labour?

This very well could be the start of your labor. A woman can lose her mucous plug a week or more before labor begins, so you can't go by that.

Time your contractions. Start timing from the beginning of one to the beginning of the next one. You should see a repetitive pattern as to how far apart they are. It really depends on what baby this is for you as to when to head to the hospital. Keep in touch with your midwife.