Hate when people stare at me??

well heres the story, my mother is on a double lung transplant list and hence has a disabled car parking space thing. i feel as if whenever we use a disabled space that everyone looks at me and my mam just because she doesnt look 'disabled' she can walk and talk like a regular person she just doesnt have stamina and has trouble breathing. i feel like people are judging us and even when they see that we have the pass thing that they think were like just lazy sods. i feel like shouting at them and telling them that just because she isnt in a wheelchair or isnt missing a fricken arm, that it doesnt mean she isn't worthy of it.
for example if we are going to a shopping centre and park in a disabled spot, i can feel people entering and exiting the shops looking at us and lingering around to see if mam actually has something wrong with her!