I had a gastric sleeve surgery 4 months ago, I only have bowel movement maybe once a week. I think I now have hemorrhoids, is this all related?

Pain Meds? Are you still taking prescription meds for pain? Narcotics can worsen constipation. Either way you want to avoid constipating, high-fat foods and increase the fiber in your diet. Make sure you are well hydrated or the fiber won't work as well. Talk with your bariatric surgeon about diet modifications that may help.
Perhaps. The hemorrhoidal plexus is a collection of small vessels around the anus . These san expand with increase of intra-abdominal pressure. Constipation is a common cause. Talk to your physician who may increase your dietary fiber.
If you are . Constipated it can lead to hormones. One thing you could try is MiraLAX (polyethylene glycol) or a fiber product. I'm not sure about the effects of the gastric sleeve on bowel habits but you may have inadvertently reduced fiber intake.