belly

I'm 19 and thin, (don't wanna sound vain) when I eat big meals my belly tends to be bloated and hard for about 2hours I usually only snack things like crisps sweets and chicken nugget, never healthy.. so last 2 days I put to mind to eat healthy like salads.
ā€‹     but lately as I've been eating salads   regualy ( fruit salad for breakfast, salad at lunch with boiled egg and cocktail sausages, and dinner chicken salad) my elly has veen very bloated and quiet hard, it hasn't gone back to normal fit 2 days!! 
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ā€‹isit diet change or culd I be pregnant!?! I've been trying for 6moths!