You should consider calling the Tampa Field Office (800-669-4000) of the EEOC to find out about filing a charge of discrimination against the employer regarding the harassment. Also, if you told the employer that you suspected the heat exhaustion was caused by work, you might have a workers' comp retaliation claim (which would be outside the scope of the EEOC), meaning you should contact an employment lawyer (who can also help with any FMLA issues and the EEOC charge). Also, if your surgery or any other ongoing medical condition relates to the heat exhaustion, you should contact a workers' comp attorney to discuss options for seeking medical care and other benefits.
The question does not explain when you were fired or the stated reason for your termination. If it was right after the comp claim and FMLA request, it is very possible you may have a retaliation claim- the employer cannot interfere with or otherwise retaliate against you for exercising your rights under the FLorida Workers' Compensation Statute or the FMLA. The FMLA also provides job protections- the right to return to your job after an FMLA leave- if certain conditions are met. Based on the information provided, I think it would be well worth your time to have experienced counsel review your case. Be sure to have your FMLA/workers' compensation claim paperwork available for counsel's review.
In addition to any protections you may have under the FMLA and the laws prohibiting discrimination, as a DOC employee you may also have the right to file an appeal of your termination with the Florida Public Employees Relations Commission. You should not give up this right without at least consulting with an attorney.