menstrualはmenstruation「生理」の形容詞です。
crampsは「けいれん」という意味もあります。
日常会話ではmenstrualの部分が省略されることが多いです。
Each month when my period comes I have severe cramps
わたしは、毎月生理が来るたびに、激しい生理痛に悩まされる。
生理痛[薬](https://eikaiwa.dmm.com/uknow/questions/11254/):anti-menstrual cramps drug(drug for cramps) などと表現されますが、実際に良く使われるのは、Pain Killer (Period pain killer)です。
Can i have a (period) pain killer?([痛み止め](https://eikaiwa.dmm.com/uknow/questions/58881/)をください。)と薬局でいえば大丈夫です。
I need to find some midol for my cramps.
I need something for my ladies days cramps.
I am cramping and am looking for some pain medication.
I need some pain meds for cramping.
Midol is a name brand of a medicine just for menstrual cramps and has also become a generic or common term for any medication specifically for menstrual cramps. So if you ask for some midol in the US they will know what you are looking for.
I need to find some midol for my cramps.(生理痛の薬を探しています)
I need something for my ladies days cramps.(生理痛の薬を探しています)
I am cramping and am looking for some pain medication.(生理痛の薬を探しています)
I need some pain meds for cramping.(生理痛の薬を探しています)
"Midol" は、生理痛の薬の商標ですが、生理痛薬全般を指す一般語になっています。ですから、アメリカでは "Midol" と言えば、何を求めているのかが伝わります。
When suffering from pain from your menstruation, you may say that you have period pain. By saying this or you are suffering from menstrual cramps the doctor would recommend you some painkillers to make it less painful.
"Excuse me. I am suffering from menstrual cramps. Is there anything I can take to make it less painful?"
生理痛があるときには、"I have period pain" と言えます。"I have period pain" あるいは "I am suffering from menstrual cramps" と言うと、お医者さんは鎮痛剤を勧めてくれます。
【例】
"Excuse me. I am suffering from menstrual cramps. Is there anything I can take to make it less painful?"
(すみません、生理痛があるのですが、何か痛みを和らげられるものはありますか)
Most of my friends and I shorten it to just, "cramps." Normally there is a head nod of, "oh I know exactly what your talking about," as there is no need to specify what type of cramps they are. As for, "menstrual pains," this is just another way of referring to cramps.