If the pain is that bad, then yes, I would back the dose down a little. Some people get pain worse than others. I get no sides of that nature at all, using Naps Hyge's, but everyone is different. I've seen one guy gain 15 lbs on a few IU, while another gained 6 lbs of water, using more, both guys using the same batch of GH.  Over time, this pain will subside and the fluid thats putting pressure on the nerve will reduce. As it does, try to add another .5iu. Stay there for a few wks, and then when you know you're safe, increase again. 

Remember that GH is a long term supp, so take your time with it and increase as you can. Even at 1.5iu, you'll still get some benefit, especially from a good quality GH, like hyge. And even if you find that you can't take it any higher than 4iu, that will be plenty to help you with your goal