Hi, I kept an Ornate monitor for almost 14 years, the 10 gallon tank is FAR too small, you will never get the proper temp range in something that size! Also, whilst they are semi aquatic, they are also semi arborial (the youngsters spend lots of time up in the trees, and so too do the adults), so you need a long, wide, AND tall enclosure, the bigger the better, they will NOT "get lost" in a larger tank (The wild is VERY, VERY large, and they aren`t predated on here in captivity, although the way some people "take care" of them, it`s the same thing (NOT suggesting you are like that), you`re asking advise, which is start. If the monitor has a discharge from the mouth/nostrils, it may be a R/I, in which case, a vet is the best option. In the meantime, you mention temps of 145f, how are you measuring them (you need either a digital thermometer/hygrometer with a probe or a temp-gun to measure the surface and ambient temps and humidity). I recommend a range of between approx 120 to 130f basking area, and approx 80 to 95f ambient (cool to warm side, daytime),and nights, no lower than approx 75f. Humidity between approx 60 to 80% or higher, (they prefer slightly cooler temps and higher humidity than the V. niloticus). The monitor MUST be given time to acclimate to the enclosure BEFORE any handling takes place, just for now, only cage cleaning, water/food etc.
Please do NOT offer a diet consisting mainly of mice (pinkies are virtually useless), the skeleton isn`t formed, and not much protein, fuzzies (cut into pieces if necessary) are a better option, but a variety of insects, small, freshwater fish etc (whole prey items only). Tell me what type of heat/light bulbs you`re using, and do you have any photos of the monitor and the tank?