1. You were granted leave on the basis of the existing rules and regulations in this regard, hence the subsequent amendment may not have an effect especially when the leave has been approved by the competent authority even though the so called ordinance may was pronounced with retrospective effect. The ordinances generally are not passed with retrospective effect.
2. You can vent out all your grievances in the form of pleadings in the proposed case to be filed before court.
3. The record of the works allotted to you are available in the hospitably records, hence there is nothing that you should be worried about proving your grievances.
4. State administrative tribunal is situated in the state capital.
5. You can file a OA on the basis of the rules in this regard venting out your grievances.
6. Your immediate boss is the dean and not the government hence you may have to file case against the dean and implead government as necessary party to the case.