2mos off/on dull intermittent ache bottom of left rib cage almost on top of stomach. Feels muscular but can also feel acidic in tummy. Any idea?

See your doctor. As you mentioned that you may have increased 'acid in your tummy', this may mean or point toward some form of hyperacidity issue occurring in your stomach that needs to be worked up. So that should be the first place to start. Also, it's important to not eat close to bedtime, reduce any form of acidic or tomato-based products, processed foods, fried foods, sodas, sugary desserts or carbs. .
Check acid reflex. If feeling acidic, accompanied by dull aches in stomach region, get yourself checked out for acid reflex which can be managed with medication and diet modifications. While many meds are OTC, a proper exam will help establish proper diagnosis.

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I have had a dull ache and pins & needles in right abdomen just below rib cage for a few days now, hurts more when I eat/drink, any ideas?

Many. Could be onset of shingles, or any number of conditions. See your doctor soon! Read more...
Ultrasound. A negative ultrasound of the right upper abdomen usually rules out gall stones and liver disease as the causes of your discomfort which may be muscular or due to nerve irritation. Sometimes sludge in the gall bladder is the culprit and it will not be seen on ultrasound. I recommend a consultation with a general surgeon if the discomfort continues to bother you. Read more...