injury advice

I've been training 3 on 1 off but my shoulder is constantly hurting do you think training every other day could aliviate the problem. I think it's tendonitis

In my expert opinion having just spent the last 8 weeks in and out of hospital seeing people of varying degrees of competency. I can 100% say that the only way to heal it will be rest. If its nothing major a few weeks rest will sort it, if its more serious then you need to see a specialist which will then take 8 weeks for pretty much every consultation and appointment and thus have it strung out over 12 months or more. 
 
 

Rest alone will result in an improvement of symptoms but doesn't address the cause. There is a reason why you are getting pain in your shoulder and you need to work this out so you can make the necessary changes. 
 
If you care about training, fork out a bit of cash and see a decent private physio.