It really does affect people differently, and if you take it consistently for any amount of time you can really quickly build up tolerance to it so that what might have knocked you out the first time barely even feels like it does anything. I'm a (in recovery!) alcoholic /addict and I used to pop tramadol like they were literally nothing. Buuuut, even the first time I took tramadol and other opioids they didn't affect me that bad, I didn't throw up or anything like when you took them. But a lot of people do. My stepdad just had his gallbladder out and a (moderate dose of) codeine sent him absolutely loopy - some peoples body's just can't 'handle' opioids. Tramadol is so easy to become addicted to tho, I wouldn't be surprised if she's dependent on them if she's been taking them for anything more than a couple of weeks.
On a side note, who the hell decants their medication into little brown bottles and puts a hipster store label on them loooool.