Couple things I want to ask. Are you using any AAS? I ask this as I get the same thing when on cycle due to water retention. Using some Adex usually takes care of the water and aleviates the pain and pumps.
Yes doing a test e cycle 500mg week split in 2 shots, taking adex about .5mg ED, only 3 weeks in so the water bloats shouldn't be the cause yet but i could be wrong, all i know is that the last two leg and back workout i couldn't complete due to the pain!
Happens to me regularly due to water. Usually Dbol is my culprit! The first few weeks is the biggest watre weight gain for me.
I would recomend upping the adex to 1mg ED for 1 week or so and then come back down and see if that works. Raising the dose should blitz out a bit more water and take care of the pumps.
If that dont work, then it there may not be anything you can do for it except man up and push through it!
Dbol is the very first thing that came to mind before seeing your cycle. I believe it is the water retention caused by the test. Use Arim, drink tons of water and add a potassium supplement. Seems to work for me somewhat.
lower back pumps....they suck especially after heavy squats, dbols and tren always give me the pumps, also nanoX9. I dont think there is a cure, you just gotta hack through it, it comes with the package