I'm on the pill and started taking tizanidine. i have been getting cramps like in on my period when i'm not. is this normal and should i be concerned?

Ask the prescriber: Do you know why you were given that drug? It does have some serious side effects that might be responsible for your troubles. Always report unusual new symptoms after starting a drug and ask ahead about possible reactions to watch for. It also may be part of why this was given to you - spasticity. Don't worry - but do ask. Best wishes!