My apartment became infested with bed bugs. Is there an organization that helps seniors with problems like this?

Call the county health department and explain the situation. They might intervene and force the landlord to pay for a complete extermination.

Search your local court system and find out if there's a landlord-tenant division, then call and see if there's any kind of pro bono legal service provided to represent you and the other tenants until the issue is resolved.

In a situation like this, all rents could be escrowed and withheld from the landlord until he meets health standards and eliminates all the bed bugs.

I agree, your county health department BUT you better be Mrs. Clean. Vacuum daily, especially all the little cracks and crevices, under beds and couches. Get some cedar closet spray to deter bugs. Febreze is very bug repellent. I put essential oils in a small spray bottle: cedar, lavender, geranium and Dawn liquid. Use 2 drops of each, fill with water and shake it up.
Strip the bed and vacuum both sides of the mattress. Launder the sheets and blankets. Toss the pillows in the dryer with scented dryer sheets.
Think like a bug. Is a space small enough to hide in? Vacuum & spray it.

I had the same problem last year in my IL apartment in Denver. The landlord asked me if I knew how they got into the apartment. I suggested it might have been from a craft show the residents held a month before. Management agreed and had an exterminator come out. The exterminator found them only in my bedroom. She sprayed everything and suggested I get mattress and box spring protectors. Management had already told me I had to have all my clothes in the closet, the sheets, pillowcases, blanket, and pillows laundered by a commercial laundry where the dried would be hotter than the dryers in our facility. That cost me a lot. It would be nice if I'd had help. I had to borrow the money.

Some people forget to retreat after any hatch in 6 wks., or however long that takes for your bugs.

Forgot to say that I investigated all possible resources to see if I could get help. There wasn't any from the Colorado Department of Public Health and Environment, the Denver County Health Department or anybody else. I had to do everything by myself.

The seats at church, the movie theatre, the bus, the senior center, any chair you sit on, your hairdresser!!! You may have to stop hugging people for awhile.
Spray with cedarcide (online) your purse, your bed, your pillow cases. Re-treat any blankets brought out from storage.

Who is visiting you?

Don't want to mention this, but you treated your hairbrushes?

I didn't need to retreat. I had no more bedbug bites after the initial treatment. The bites were what alerted me to the bugs.