For the last few days i've had a pain in my right shoulder blade (pretty much in the middle) and my right armpit feels a little strange. advice please?

Likely muscular pain: Inflammation and irritation of the rotator cuff muscles of the shoulder can cause discomfort in this described region. Pain can occur from a minor injury or muscle overuse. Short-term treatment (<1 week) with an over-the-counter pain medicine like acetaminophen or ibuprofen can help provide relief. Seek medical attention if pain persists beyond 1-2 weeks to rule-out other causes.