I also had a very sore neck and it the tissue felt tender to touch. Turns out I had what is called a gorder and gravesdisease (hyperthyroidism). I had to have my thyroid gland removed. If you have not had your thyroid gland check it my me worth a shot. I hope whatever it is you find out soon and get to feeling better. Good luck!
Your sed rate or (ESR) can be high with any cause of inflammation such as Rheumatoid arthritis, anemia, lupus, pregnancy, etc. Do you have a sore throat? Have you had your throat checked for a strep infection? You could also perhaps have mono if you had a sore throat, swollen glands and high fever, fatigue etc. A lot of things will cause high ESR and swollen glands. What other symptoms do you have?