Assuming the trailer runs "level" with the truck, not nose high. Some big rig trailer repair shops can check axle alignment. ASH, auto safety house I think does too.
You may have clipped a curb and tweaked the axle.
Invest in a infa red temp gun. Harbor freight as cheap as 10-20 bucks.Temps will tell you a lot about whats going on.
Whenever I stop, I check all the tires to see if any are running abnormally high compared to others, axle temps etc on tow vehicle etc. After a while you see an average temp on tires etc. ( I have a on board TPMS for the RV too)
Check tire/rim temps etc. my 3 axles, front(towards truck) is cooler,more air flow, center 5-10 degrees more, rear about the same as center.
In Az, my tires usually run, depending on the season, 110-140 degrees.I got tired of tire issues and went to 16" with Bridgestone duravis R250's and have not had a tire issue since 2012 when I switched over..I'll probably jinx myself by saying that, but going to 16" was the best thing I ever did to the RV.
It does sound like you have a axle issue.