Arms in pain

Hello, My names Stuart and I'm a budding freelance musician. Recently I've been booked for quite a few low paid gigs to try and help me kickstart my career but the issue is I play a very heavy instrument with an even heavier case. My appeal is for money to buy a Lightweight case that will go on my back and make carrying to and from when travelling (big distances) much easier. As it's christmas...I'm hoping you are all in the spirit of giving and I would be incredibly grateful. I often do Charity gigs for free but my arms are in pain for days after due to the weight and carrying. I'm not a tall nor strong person. Any help is appreciated. You would be helping me help more people!   Please -S