34yr old with pain behind right knee into top of calf when bending leg or walking. dont see any bruising or swelling. how to tell if its a blood clot?

Potential diagnosis: Bakers cyst (possibly irritating the nearby nerves or vessels resulting in the tingling, baker's cysts are often associated w/ meniscus (cartilage) tears), blood clot (dvt), stress fracture, muscle/tendon strain, herniated disc (in back causing knee pain). W/ your symptoms i rec you seek advice from your pcp or ortho as soon as you can. Either of these physicians can order further tests if necess.

Ultrasound: The only way to definitively say if you have a DVT or not is to have an ultrasound performed.