Burning sensation down front of both thighs to the knee. is this a sign of something worrisome? convinced i have a brain tumor or ms

You ARE a worrier: Your symptoms are absolutely, totally, completely not typical of either MS or a brain tumor. Stop making these seven-league jumps to conclusions. It sounds like bilateral meralgia paresthetica. Bilateral suggests a condition like being very overweight or very underweight or having some undiagnosed predisposition to mononeuropathy. See a doctor & get it checked out.