You said you are still on Probation period. During this period, you are always liable to be terminated without assigning any reason or notice or pay in lieu of notice. Only on successful completion of probation period, a notice period is to be given by either party for termination of service.
You can put up your resignation stating the reasons for the same and supporting it with Medical documents with immediate effect without serving the Notice Period.
No legal action can be taken against your , in your case. 9th February 2015 From India, Mumbai