Left side back pain after right THR

@tct Bingo! You have most likely hit it right on - now you need to concentrate on standing upright and walking straight. After hip replacement, my PT strongly suggested new shoes as well - at least the everyday ones, because all the recently worn ones were "imprinted" with my limping gait from before surgery.
If self-care doesn't help, I would suggest a few sessions with a rehab therapist to work on your gait. Mine was so messed up after 2 hip replacements and several revisions that my PCP suggested seeing a back surgeon - but the ortho sent me to PT - it took several weeks to work it out.

Have you mentioned this to your surgeon or a PT?

Thanks for your comments and advice. I did buy a new pair of walking shoes. I plan to mention this to the surgeon next time I see him.

Was it a posterior or anterior THR?
I have had 2 Anterior THR and did not have any back pain.

I had my left hip replaced using Superpath and zero pain (everywhere). Definitely do PT. Before my surgery i thought I had a left knee issue as well; once I replaced my left hip the left knee pain went away also.

You need a good physical therapist and need to spend some time with her. You should also be seeing your surgeon and she should be reviewing x-rays to make sure that the replacement is properly seated and the bone properly growing around it.

Superpath?

https://www.chowhipandknee.com/superpath-total-hip-replacement-hip-knee-specialist-phoenix-arizona/
Dr. Chow was the primary inventor of the methodology and I was fortunate that I had him as my surgeon. The morning of the operation he walked into the outpatient clinic with the multipage hospital document on what to do and what not to do after hip surgery (don't cross legs, don't bend, etc.). He tossed it in the wastepaper basket and said "just take your medicine and be a couch potato for five weeks as the one thing I can't do is make bones grow". His medicine was oxycodone and Celebrex with instructions to take one oxy the first night, then continue until not needed and then taper off. I took the first one. The next morning I called up and said I had no pain, can I skip the rest of the oxy and he said yes. Two days later I repeated the same with the celebrex. So bsaically, post operatively no medicine, no pain.

The Superpath methodology is slowly being rolled out nationwide. There are three current primary methods: posterior, anterior and Superpath. From what I have read they all ultimately have the same outcome but the pain level and speed of recovery is better with anterior than posterior and better with Superpath than anterior.

BUT...to me the more important consideration is surgeon skill and experience. I would rather have a surgeon doing posterior for me (the method I would least want) than another doing Superpath (my preferred method) who has only done it once or twice before.

But if I can have an experienced and skilled surgeon, all other things being close to equal, I would choose Superpath.

It was Anterior. Chiropractor has diagnosed as SI joint issue and is treating as such. We shall see.
Also, I see the surgeon again in 4 weeks (12 weeks after surgery)

Sixteen months ago, I had left hip replacement. I too have some numbness in my left thigh and a dull pain in the hip; however, it comes and goes. It does often bother me in the night when I sleep on that side. I do lift weights, do daily squats, bridges,some lunges and walk approximately 5 miles a day. I probably am 5 lbs. overweight. Any suggestions on whats going on with this irritation?