Sick feeling while nursing

I feel nauseous and lightheaded nursing my 6 week old. Its been like that since my milk came in and it only happens when she is latched and eating (pumping I don't feel sick). I mentioned this to my OBGYN at my check up and she said it is due to the brain chemical oxytocin released during breastfeeding. The feeling may or may not go away over time. Has anyone else experienced this and did anything help relieve your nausea?