A week ago, I woke up with an achy neck which I assumed was due to sleeping awkwardly. However, the next day it persisted and it still aches. The pain has mainly been on the left side and prevents me from turning my head fully to my left. What should I do

I . I should start by saying that I am a firm believer that western medicine plays a most important role in medical care. Certainly a lymph node that is new and not going away should be evaluated. However to address the neck situation (something as a surgeon looking down during a case for many hours knows something about) you may want to consider massage therapy and/or a chiropractic evaluation. While I am not trained in diseases of the cervical spine, i can tell you from personal experience it has been great for me.
Since . Since you have trouble turning your head and you feel achy, your neck muscles are tight and may respond to stretching or manual treatments, moist heat for 10-20 minutes per hour as needed, and over the counter medications such as Acetaminophen or ibuprofen. The 1.5 cm mass in the posterior part of your neck, under your earlobe may or may not be related to your achy neck. If it is an inflamed lymph node from an infection, such as a systemic virus, or local bacterial skin infection, it will be tender to touch, and may cause the local muscles to be tight and sore, but not always. If the enlarged mass is a lymph node that contains another disease, such as cancer, it would typically be very firm and not always tender either. A physician can distinguish between these conditions and make an accurate diagnosis. An osteopathic physician can also manipulate your neck muscles if that is needed as well as tell you whether the mass is a lymph node, or a different type of mass, and whether further workup is necessary. The lymph nodes on the left side of your collar bone that come and go should also be evaluated. I have seen some diseases that cause lymph node enlargements sporadically, and those should also be evaluated by a physician. An internal organ problem in the chest or abdomen can cause the left sided lymph nodes above the collar bone to become enlarged. It would be important for your physician to evaluate your heart, lungs, stomach, and liver and spleen for enlargement or tenderness. Blood tests and x-rays may be indicated. If you have fevers or chills, weight loss, or other symptoms, seeing your physician sooner than later is recommended.
The . The lymph nodes in that area can normally be that big and may enlarge in response to infection or inflammation. Other masses in the area can be masses from birth that have continued to grow, normal and abnormal blood vessel masses, under the skin cysts and masses, and muscle or fat masses. Sometimes lymph vessels are particularly tender due to chronic infections like mononucleosis or ebstein barr virus. Try taking some pain medicine like tylenol (acetaminophen) or motrin, but if it persists, consider having it evaluated by an otolaryngologist. I hope you feel better and become pain free.