My Suggestions
This is not the end of the world. I would like to suggest that ---
1. Looking for a new job ASAP. I know this is very tough market now. But I think this is the only best way. The new employer needs to support your H1B.
2. Try to ask your current company to keep your I-485 going, actully all they need to do is that do not revoke your I-140 petition. Try and try and try!!! Try very hard to explain your situation and to be reasonable and not show your panic. Also try to ask them to issue a letter that states they will re-hire you in the future when your I-485 gets approved.
3. Leave-on-absence is an option and according to the law, when you have health problem or your family member has health problem that you need to be with them, the employer can not terminate you. But you might required to show the doctor\'s paper. As to each company, they might have different categories for leave-on-absence, ask your HR to see if you can use them.
4. Be careful using EAD card for your new job, most company has either HR or Immigration lawyer, they can very easily find out your status and I don\'t think it is a good idea to use it if it is less than 180 days.
5. Try to hire a lawyer just for consultation, you might have pay a small fee, I think it is worth. WE ARE NOT LAWYER.
Just my opinion. Good luck!