Baby doesnt want to eat

My baby has been having solids since 4 months old, and shes always been food obsessed, she would clear her bowl in minutes and eat anything that was given to her, she likes all fruit, veg, chicken, toast, potato, cheese, yogurt everything. Shes 7 months now & for the last week or so she wont eat anything. We sit down for her meal and all she does is suck her lips in and turns her head away at food, even her usual favourites. Shes literally eating about 2 or 3 spoonfuls at each meal now, but shes not having any extra milk to make up for it either, shes just not hungry ever. The only time she will eat is if she is having finger foods and feeds herself, but shes not too good at feeding herself and most of it ends up on the floor or over herself, so shes not getting hardly any food that way either. Should I be worried? Its suddenly got really hot here in the UK so could it be the fact its too hot? I know i dont feel like eating much when its hot either but not sure if its the same for her.