Fludrocortisone and Midodrine are both medications that can help raise blood pressure. Ask your physician if one of these medications would be right for your situation. People are not generally prescribed medicine for low blood pressure, as it's not often a cause for concern unless it presents with symptoms.
Why do the middle fingers lock up when experiencing pain in neck and shoulders?   One cause could be some kind of impingement (pressure or swelling that applies pressure) of the spinal cord at C7, one of the cervical segments of your spine.
Trigger finger may happen because a person performs the same manipulation over and over on a job, from squeezing and gripping during a weekend of heavy pruning and gardening, or from such hobbies as playing a musical instrument or crocheting. Trigger finger may also result from trauma or accident. The symptoms of trigger finger are pain in the fingers and popping sensations. Sometimes the finger may lock down into the palm or lock out straight. Symptoms are usually worse in the morning and improve during the day. Diagnosis. The diagnosis of trigger finger and thumb is obvious on physical examination. Often there is a click that can be felt as the nodule passes through the sheath.