No mention about the post held and the length of your service. If you are a workman you can seek remedy under the Industrial Disputes Act,1947 against your non-employment arising out of forced resignation. But, you should bear in mind that you have to prove it which I think is very difficult.
You may also look at the issue from a different angle. Admittedly your continued ill-health compelled you to go on leave so frequently that your employer had to ask you finally to resign. Step into his shoes and see how an employer can accomodate a sick employee forever. After raising the dispute, suppose he takes you back into service and the same situation continues, subsequently you can be sent out formally on the ground of medical invalidation.
So, your decision depends upon your health condition. If you suffer from any chronic disease that requires constant medical care, you can choose some other suitable alternative employment or self-employment as the case be. There is no disclosure about the efforts taken by you for a smooth separation.