refusal to feed after 5 mins

Hello this is my first post,
My baby is two weeks old and I am having trouble breastfeeding. At the
moments she will take no more than 5 minutes at the breast before becoming
distressed and crying/screaming. She then falls asleep and refuses to take
anymore from breast or bottle. I am worried that she will not be getting
enough feed - I have had no visit from a health visitor as yet so am unable
to judge my babies health - weight gain etc. In the last 8 hours she has
only fed for about 16 minutes in total - I am woried - can anyone offer any
advice
Thankyou