When i woke up, i stretched and got pain on my lower leg muscle. could i have hurt myself?

W/c leg muscle group: Lower leg muscles; w/c group, anterior (edl, ta) or posterior (achilles tendon)? If anterior lower leg, you could have strained the edl or at muscle; if posterior, the achilles tendon (=heel cord, w/c is attached to the gastrosoleus). In either case, the pain should improve gradually. Otherwise, you need to make an appointment with a foot and ankle specialist for proper evaluation.