How do I get help?

I am afraid I am far from being above reproach in that I would get this done and I would lie to do so were I to have to. That is that I would "fudge" the truth. That is what our system has become, unfortunately.
Your wife MAY have a UTI and that can cause sepsis and death. I believe that I would call EMS and have your wife transported to ER with whatever excuse or story you need to make up to do so. There they will get a cath specimen of the urine to diagnose and treat. You say you are currently unable to handle your wife. I would stress this and say she is badly in need of assessment. If you can get her admitted you should AT ONCE contact Social Services on an "emergent" basis and tell them that you are unlikely to be able to physically take care of your wife at home any more; that you need placement and discharge planning for her.
That is all given you are ready for what sounds like it is coming sooner than later, and hopefully before sepsis claims her life. I am so sorry you are going through this and I wish you the very best.

I am with funky here. UTIs are serious get her to ER. Talk to SW as Funky says. Do not let them tell you there is in home help. Its expensive and what Medicaid offers is very little. Tell them she needs to be placed in LTC. You can no longer care for her or want the responsibility of dealing with aides that may not show up or you can't get enough hours.

If you do get her LTC, then see an elder lawyer about splitting you assets for Medicaid. Her split will go to her care and when spent down, you can apply for Medicaid. There is more to this that an elder lawyer can explain.

Take her to the ER and have her checked for a UTI and when there tell them that you can no longer care for her at home and she needs to be placed. The hospital social worker will help you find placement for her.
Do not under any circumstances let them talk you into taking her back home as they will surely try.
Instead, stand your ground and let them know in no uncertain terms that it's just too much for you now and she needs to be placed.
Best wishes.

Are you your wife's PoA? If not, and you're not even her Medical Representative (a HIPAA form your wife fills out at the doc office) then this may explain why her doctor *can't* do what you're asking. It doesn't happen just because you're her husband.

To get her in for an exam you may need to use a "therapeutic fib", telling her an annual exam is required in order to continue to get Medicare or SS benefits. Once you get her in you pass the doc a pre-written note telling them to check her for a UTI. At this point I would NOT ask for a cognitive exam since she may have a UTII and this will impact how she does on that test. Please know that other health problems besides UTIs can mimic dementia symptoms, like thyroid issues, HBP, ddiabetes, dehydration, vitamin deficiency, and others.

My family paid a neighbor (who was already a professional caregiver) to come in to help my Aunt have a showerr twice a week. Sometimes having a neutral person manage it is more productive, and less stressful for you.

You can consider calling facilities to come and do in-home assessments for your wife.

Try Respite Care. The 'respite' is for the carer, not the 'patient', so it shouldn't need a prescription/ referral for your wife. If your doctor won't help with the need for a UTI test, you need a different doctor.