My thermometer tells me what the high and low was for the day. For two days in a row my high has reached 102 degree and my low has been 97 degree. Any tips on how to completely fix this?
There very well might be nothing to fix, your thermometer is measuring the 'air' temp and that can easily swing with the cycling of heating elements, depending on the swing of the thermostat circuit... The mean average of 102° and 97° is a dead on 99.5° and that very well might be your internal egg temp... In the end internal 'egg' temp is what is important, and to measure that you can construct a fake egg...
I use 4oz and 2oz (premie) baby bottles configured like bellow, this is a 4oz bottle with the nipple inverted it holds give or take 3oz and that is a good size for peafowl eggs but will also work pretty well for standard chicken eggs... A 2oz bottle though would be better for chicken eggs if you are going to purchase one...
Fill it with water and put a thermometer in there and monitor that temp... The nipple acts as a gasket, especially slow flow nipples that only have a single hole...
Another option is to take the fake plastic Easter eggs, and using 2 part 5 minute epoxy seal up any holes (most nowadays have two holes on the end) and then glue the thing together... Next take a say 3/16" drill or about and drill a hole in the side, get yourself some medical lube (aka KY jelly and fill the egg up) then take a small piece of duct tape and close the hole well... Next take a nail or what not and put a small hole in the duct tape and force a thermometer in there... The duct tape will act as a gasket and since the medical lube is thicker then water it won't drip out as easily, especially if you position the egg hole upwards... Eventually the medical lube will dry out but you should easily be able to get a few incubation cycles out of it...
Another option some suggested was to fill the fake egg with water absorbing crystals and water, they can be found in the garden section for planted pots, in the toy isle as 'squishy baff' or if you have access to a baby diaper, rip it open (carefully) and empty out all the little sand like beads... That stuff will absorb about 800x it's weight in water and become like thick jello or tapioca putting and won't easily leak out of the egg...
Or the quick and dirty one that doesn't last all that long but is cheap, take a ziplock bag, put in 2oz of water, get as much air out as you can and zip it shut, roll, scrunch, clump that bag around the end of a thermometer so the thermometer is in the middle...
There are also commercial fake eggs but they are costly...