Just a quick update.
I figured out the cause of the problem; the potting soil that I bought is from the same company that I buy my seedling mix from.
This new mix is called “Professional Potting Mix”
from Culterra.
I usually buy their outdoor potting mix which contains larger bark chips.
So this time around I asked the owner of the plant centre for a finer mix. She suggested that I try the “Professional” -type. Unbeknownst to us this mix contains slow release fertilizers. So when I added my own compost to this mix, I accidentally overloaded the soil and made it very “hot”.
Thusly, three days or so later the soil started releasing it’s own fertilizers and everything went to hell.
I have re-potted nd rebagged them with the old outdoor mix and they seem to be recovering.
I just want to thank you guys for the quick replies and awesome feedback 
.
As a new grower, I really started panicking - especially at the fast rate that things were going wrong.
I did get hold of a ph and tds meter so I am feeling way more confident.
