It's very frustrating when your favourite sport / hobby is threatened by some misadventure.
You probably don't want to hear it, but a personal tale. I had to give up playing squash at a high level because of my back. Eventually, I had to decide: would I give up before the back operation, and perhaps there wouldn't be one (twenty years later I'm still ok), or a couple months later, after the operation?
I was very grumpy for six months, and then... I discovered a sport even more exciting than squash. Flying gliders...
I'm not saying you must give up weightlifting but, if you have to... there's another sport waiting.
Would you know by any chance if the arterial pulse in your wrist has been effected? Did anyone ever test the pulse, whilst you turned your head, looked up and simultaneously took in a deep breath? Adson's test.
In your case it seems that the vein bringing blood back to the heart has been effected, hence the swelling and discolouration of your arm.
If that's the case, and I fear it is, then it's not likely that Chiropractic can help you. The vein doesn't actually go through the thoracic outlet, between the scalene muscles.
But back to the pulse in your wrist. It is of course possible that the artery and brachial plexus also to have been effected, and there chiropractic may be able to help. But... if that vein has been contused, there would be some risk.
Frankly, this is a complex case. It's not for me to make recommendations.
The artery and nerves pass under the Pec minor tendon, and perhaps tests suggest they are being pinched there, hence advocacy to lose muscle mass.
I can't see lowering your fat % helping.
Sorry not to be more positive and helpful. Give us an update in a couple months.
Dr B Find a good chiropractor
may be your next step.
Dr Barrie Lewis