I feel like my mattress is pushing my hips out of alignment

you weigh 280 and you bought a cheap Amazon foam mattress? There's your problem. That thing is probably 3 inches of memory foam over a cardboard box. At your weight, you need something with actual support, not a marshmallow.

Could also be the foundation. Are you using a box spring or slats? If the base is flexing, the mattress will too. I had a similar hip issue and it turned out my slats were bowing.

3 years is about right for a cheap foam mattreds to die, especially for a heavier person. The foam loses its pushback. You need a hybrid with coils or a dense polyfoam base. Foam alone at 280 lbs = hammock.

Side sleeper + heavy + sinking hips = you need a firmer surface so your hips don't sink lower than your shoulders.Otherwise your spine is a zigzag. Try sleeping on the floor for a night to see if the pain goes away, then you'll know it's the mattress.

I'm 250 and had the same issue. Went to a local mattress store and the guy put me on a latex hybrid. Night and day difference. It's firm but not brick-like. Cost me $1800 but my hips stopped screaming.

Floor sleeping is free but your back will hate you in a different way. Honestly, at 280 you're in the 'heavy sleeper' category where most mattresses just aren't built for you. Look for something with a coil coil gauge of 13-14 and high-density foam.

Have you checked if your mattress is sagging? Put a straight edge across it. If there's a visible dip where your hips go, it's done. Memory foam especially degrades faster for heavier folks.

Also, are you using a mattress toper? Sometimes people add a soft topper to fix firmness but it just makes the sink worse. Remove any extra fluff and see if that helps temporarily.

Latex is great but pricey. A cheaper alternative is a firm innerspring with a thin comfort layer. Just don't get pillow-top. That's just extra foam to break down.

I weigh 310 and I've had good luck with a big-name firm hybrid. It's been 4 years and still no sagging. The key is to rotate it every few months. Also, a mattress protector that's breathable helps keep the foam from breaking down from sweat.

Rotating is important. i forgot to rotate mine and the hip dip got worse. Now I set a reminder on my phone.

You could also try a firmer mattress with a soft topper that you replace every year. Cheaper than buying a whole new mattress when the top foam dies.

What's your budget? That's the real question. At 280 lbs, you're going to need to spend at least $1000 for something that lasts more than 2 years.

Check the warranty too. Some companies void it if you don't use a proper foundation. And they might prorate. Not worth it for a cheap mattress anyway.

I'd also suggest trying a mattress with zoned support. It's firmer under the hips, and softer under shoulders. Helped me a lot.