After the roof leaked through our bedroom ceiling

The landlord is responsible for all costs

Yep! Let the landlord know. It his job.

Landlord isn't worried about mold and plans to do as little as possible. I will first have to prove the mold exists to get any action from him. How can I get a test for mold that is accurate and affordable?

From a previous DIY I have posted the link for an article that has some DIY kits.

https://www.homemoldtestkit.com/how-to-detect-household-mold/

I had the same problem with my landlord several years ago. The home testing kits aren't very reliable. I finally bit the bullet and paid $350.00 to have my house professionally tested. It was worth the money as we used that information to end our lease when the landlord refused to remediate the issue.

The landlord is responsible. Call the city inspector.

Thanks to all who responded.

ThewitchskitchenHometalker - Mold is dangerous and with your medical condition it could be come worse. First I would contact the landlord and explain the situation and let him know you will be calling the City Building and Health Inspector. Then see what his reaction is. Nothing done, do not pay your rent. Open a saving account and place all your rent money in this account. File a small claims judgment against him for not making repairs. If you go to court you can prove you have all funds if he makes the repairs. This a long way to go but this will cause him to take action or let you out of your lease. Record all conversations in writing and send all notices to the landlord by register mail for him to sign when delivered. Look at Cindy768, you can tell the Landlord about this procedure.