Domestic drains / toilet overflowing

Hi All,

looking for some opinions on this problem. I moved into a house in aug, no issues with plumbing until these last 2wks with all the rainfall. pool of water about 2" deep has formed outside our back door, it's rain water.

on top of that the water level in the toilets is very high, when we flush it rises right up to the rim, it doesnt fully go down. when i empty the water out (with a jug) it gurlges when i get down to the correct water level.

we've had the septic tank emptied this week as a precaution, still the loo water level is rising.

the guy that emptied our tank suggested that the rain water drain was overflowing, and that could be causing the issues. when the rain stopped and the pool of water in the garden disappeared, our toilet water levels went back to normal. i'm wondering how these 2 could be connected??

help!