I'd say contact your bariatrician and ask; they'll know best what might have caused it!
Depending on the type, it could be due to absorption problems that it creates (Also why the doc wants you to up your protein intake; your ability to absorb it is reduced). Each gastric bypass type (sleeve,Roux en Y, Billroth, etc) has its own particularities.
Did you eat protein as in meat/yogurt/etc or protein drinks/powders and that like? It could be that if you ate that without any actual 'food' (aka, as a protein juice) your body was unable to handle the sudden influx or didn't respond well to something in the supplement due to your altered digestive tract. There are protein supplements geared toward post-bypass patients that designed with ease of digestion and ease of absorption in mind.
Again, your bariatrician will know more.
| current weight: 150.0