First of all, your LL has no right to test all residents of the apartment complex for health issues under any circumstances. Second, you do have subpoena rights in small claims, but your assumption as to the testimony of these witnesses may not be justified.
The foregoing is not legal advice, and nothing in the foregoing shall be deemed to create an attorney client relationship. If you feel you need to speak with an attorney regarding your issue, it is recommended that you contact an attorney with expertise in your area of inquiry. The information related above is purely for informational purposes, and should not be acted upon without speaking with qualified counsel familiar with you specific situation and the laws related thereto.
If there are witnesses you want compelled to testify, contact the court and request they be subpoenaed. You have the right to appeal any decision, but that's a road you probably don't want to go down.