my 6 week ld was feeding really well sometimes 5 oz a feed now she seems to have taken a nose dive gulps down the first half then struggles with the last bit , she holds her wind a lot last night feed at 22 30 she only took an ounce when she woke a 3 this morning she gulped her food bought most of it back up and then was unsettled and took 2 ounces again at half 5 is this normal