My 12wo has been a good feeder, until this week I had mastitis and have taken a course of antibiotics which I finished this morning. Now she is becoming unhappy when feeding. She seems to latch on and start feeding happily enough but after 5-10 mins is pulling away crying. Have tried different positions but that has not changed anything. She is doing it on both breasts and I feel upset and worried about her getting enough food. Please help!