My stomach started getting upset quite often since I moved here.
After I moved here, I started getting an upset stomach all the time.
ーMy stomach started getting upset quite often since I moved here.
「ここに越して来てからお腹を壊すようになった。」
my stomach started getting upset quite often で「よくお腹を壊すようになった」と言えます。
ーAfter I moved here, I started getting an upset stomach all the time.
「ここに越して来てから、しょっちゅうお腹を壊すようになった。」
I started getting an upset stomach all the time. でも「しょっちゅうお腹を壊すようになった」と言えます。
ご参考まで!