My doctor just switched me from 10 mg paroxetine I took for 19 days to lexapro (escitalopram) generic. Will I have withdrawl from paroxetine? Worried. I have G.A.D.

No. 10 mg of paroxetine is too low to cause symptoms of "discontiniuation syndrome." In any case, escitalopram would cover them, anyway.
Probably not. Not after only 10 mg for 19 days. I hope the new agent works well.
Switching SSRI's. By and large, switching from a relatively low dose to an equivalent SSRI should not be a factor to go through a withdrawal from Paroxetine, if are started on new SSRI, such as Escitalopram.