I've been taking Minoxidil twice per day and lately I've been having chest pains and shortness of breath.

If you are having shortness of breath and chest pains go see a doctor ASAP. It may be a side effect or a heart attack.  Call your doctor now.

You should see your primary care physician for an evaluation asap. These symptoms may indicate another problem and may not be a side effect of the drug. I would discontinue minoxidil until other problems have been ruled out.

You need to discontinue minoxidil and consult with your primary doctor ASAP.  Minoxidil or Rogaine is known to lower blood pressure and orthostatic hypotension (sudden drop in blood pressure in standing position) is one of its side effect. What you are experiencing might not be related to minoxidil but they require immediate attention to rule out other medical conditions.

Minoxidil is an antihypertensive medication that works by dilating blood vessels. It originally was in a pill form called Loniten.  They discovered that one of the "side-effects" was increased hair growth and then formulated into a topical solution that we now know as Minoxidil. It was approved by the FDA for baldness in 1988.Since it does have potent effects on the cardiovascular system, and you are having shortness of breath and chest pain, you should seek immediate evaluation by your physician.  It is unknown if the minoxidil is causing your chest pain/SOB, but either way, you need to see a physician asap.

Yes, you should stop immediately and get medical advice right away!Minoxidil has rare side effects on blood pressure, heart rate and other cardiovascular parameters. Take this seriously and seek medical attention in person.

You need to consult with a cardiologist right away  to role out other causes just to be sure. In addition you need to stop using rogaine at this point. 

such as you report should bring you to your doctor for an examination. Such side effects may indicate some heart or long problem so please see your doctor as this may not be solely a drug side effect