You may have a proper claim for a disability discrimination
complaint and/or a lawsuit for an unfair termination. It's a little iffy because you didn't finish the training, but it sures sounds like it wasn't your fault. In fact, you may have a cause of action against your department and the training facility for putting you in a position to get so ill.
If there are enough employees, you have the right to file a complaint with both the state discrimination agency and the federal one, the Equal Employment Opportunity Commission (EEOC).
In MO you can contact the state agency here: http://erd.dli.mt.gov/humanright/complaint.asp
You can contact the EEOC here: http://www.eeoc.gov/ (there's a ton of great information at this website!)
If you start with the state agency, in most states they'll file a complaint with the EEOC on your behalf at the same time.
There are deadlines for filing, so don't delay!
Complaint investigations are free. They're not always the best, XXXXX XXXXX do get a free investigation. If it looks like they are going to file a "no cause" finding, withdraw your complaint before they do. That way, if you go to court, a "no cause" finding can't be used against you.
You may also want to talk/consult with employment and/or trial attorneys "on the ground." A local attorney will have a better idea of the local jury pool a lot more than I could have. A conservative jury may decide in favor of your employer just because it's a law enforcement agency.
Don't actually HIRE an attorney without first checking references. And don't try to pick the attorney's brain on the phone. Schedule an appointment and visit the office, like you would for a doctor!
A couple of places to look (for someone with at least five years experience):
As a public employee, unless you were still in probationary status, you should have been given the right to a hearing prior to termination. There may still be an internal way in which you can ask for a hearing and/or appeal. For example, if this is a city department, you may be able to appeal to a local Board or to the City Council. I'm not sure, because this varies from state to state.
May I be of any further help to you today?