This does not look serious , this type of pain you describe could be product of several conditions like the presence of a Baker's cyst ( which is a fluid filled sac in your knee ) , iliotibial band syndrome ( in which the iliotibial fibrous band become swollen ,irritated or inflamed by its repetitive use ) , strained or torn muscles/ligaments or tendons ( specially the hamstring or popliteus muscles),chondromalacia patellae ( a softening of the kneecap cartilage ), bursitis ( lubricating sac inflammation) or a meniscal tear ( the meniscus is the cartilage that connects your thighbone to your shinbone) .
A minimal possibility would be knee osteoarthritis( over the years and when we get older ,some people experience cartilage loss and degeneration , without that cushion ,the joints rub against the other producing mild to severe pain ).
What you could do in the meantime, is applying ice pads ,elevate your legs , continue taking your anti-inflammatory medication and use a thigh elastic bandage ( which you can get over the counter ) to wrap your thigh and knee . That usually works ,if the pain does not improve within 3 days , You should consult your doctor for a further medical evaluation .
In your case like you are going to Mexico on Tuesday where you do not have medical care and You will not be here , although I do not think you need a corticosteroid injection right now , it would better to consult your doctor tomorrow if the pain does not get better by the end of the day .
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