Without further information, it may be hard to give a reasonable opinion. Here are some key issues : Is your medical condition hindering you from taking care of your individual needs such as hygeine, ability to prepare meals, drive if needed to a hospital, dial 911 emergency?
If any of these answers are yes, then the other key issue is that if you are not physically able to care for a child, then you are doing them a dis-service by fighting for custody. It sounds harsh, i understand as a parent i would tear any person apart that would get in the way of me parenting my daughter, however in your case this is a separate and delicate situation.
In fact, you have every right to feel discriminated against, but that is because you are personally feeling some hurt over it, and that may never go away. Is it more important to be involved with your child and do the best that you can or to allow them to feel loved but not recieve full care? No doubt, you love your child.
If you are not effected on such a large scale as I have described as being unable to perform these duties for yourself, such as paralysis to only specific limbs, or areas, but able to complete needed tasks with little or some assistance, then I apologize. Its noble to do your best, and still want to be the best parent you can in this situation no matter what, and no one can take that from you. However, it is noble to be able to say "If I am not the best for you now, I want you to have the best, and I will be with you as much as possible and thats a promise."
Good luck, sorry to hear about your situation. I am very lucky and need to revisit somethings that I may not appreciate to the full extent. So in some ways, I answered a question and offered you help, but ive recieved something from this as well.