We can offer advice and sympathy here, but kitty needs to go to a vet. We can neither tell what is wrong, nor tell you how to fix it at home.
Keep us posted, but please, get her to a vet.
I just read your post. Your kitten needs urgent medical care from a vet.
Your kitty needs to be examined by a vet urgently. How did your two
month old kitten get outside in the first place? Please take your dear
little kitten to the vet. Don't wait. You say she's not bleeding on the
inside. However, you don't know what injuries she has sustained on
the inside of her little body as a result of being run over by your mother's
truck. I can't stress this enough. Bring your kitten to a vet asap, even
today if possible. She sounds very ill. The yellow liquid could be bile.