There are tons of really good diabetes meds out there, so if you can't use metformin I'm sure your doctor will find an alternative. Metformin is simply the first drug that nearly every type 2 is started on. As for your sick days and blood sugar that goes awry on these days......well, don't worry about it.
Type 2's take blood sugar readings to see if their meds are working, if their diets and exercise are working, and if there are any longer term adjustments that have to be made in their medications. Your day to day readings are not critical like a type 1 who actually uses the readings to figure out how much insulin to take multiple times a day. If you have a bad day; c'est la vie. As long as your numbers don't stay elevated, the occasional bad day is just part of being diabetic.
For most new type 2's with an A1c over 7, the most important finger stick is the one in the morning (the fasting blood sugar reading). This is the one that tells you if your meds are doing what they are supposed to in general. You'll read a lot about after meal blood sugar readings and taking a reading for this and that, but the morning reading tells you if you are in the safe zone and lets say 2 hours after lunch tells you if your sugars are staying high enough to do damage to you. Basically if your sugars stay over 150-160 for more than 2 hours you've done damage somewhere in your body, so thats why the 2 hour reading.
Again, don't sweat the odd day. If its not part of an upward trend, then relax, we all have those days.