Lump on left side of neck just under jaw line, can only be felt when i tense muscles and when i lie on my side it sits on jaw tender to touch. cancer?

Unlikely: This "lump" sounds like it could be a lymph node. Lymph nodes can enlarge and often feel tender if you have an infection. Most times they go away on their own as your body fights the infection. As a general rule, lymph nodes due to cancer are not tender. If the lymph node enlarges or if they increase in number, please visit your physician for an examination.