I was pressing under my jaw to feel for lymph nodes (i think i was actually touching some muscle tissue that i thought was a big lymph node). since that day, whenever i turn my neck or press on it, it makes a clicking sound. no pain. what can it be?

Muscle strain: It does not seem serious and you may watch and wait. If you get restriction of movement or pain on rest, it would be prudent to see a doctor. Have a healthy diet, exercise 30 minutes/day, drink plenty of water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/. Get HPV vaccine. Wish you good health!