Welcome to the forum, pmarshall. There is no set amount of time that an attack can last – it can be from minutes to hours and will depend on what triggers it. You may want to check out our FAQ’s at the top of the page for more details and description.
I hope that the Procardia works better for you than the Norvasc did, and let us know how it goes. As with any medication, it may be a week or two for your body to adjust to see if it’s going to give you any relief, and, a rheumatologist would be the preferred doctor to monitor you while on it, if you aren’t already seeing one.