Ten days isn't long enough. Many people tend to make this common mistake, due to time and/or lack of tank space, or some other reason, only to find their older axie resident ends up suffering (ie becomes sick or stressed). This may not be the case but keep an eye on them both and she shows any other signs over the next week/s, then separate them.
If you don't have test kits for ammonia/nitrite and nitrate and have the time within the next few days - take a sample of tankwater to your petshop; ask them to test for them and write the results/figures down in a book and keep it by your tank. Basically if ammonia/nitrite levels are above 0, then you need to do 20=30% waterchange every day/every two days to bring the levels down. No need to add chemicals to fix (other than a dechlorinator to remove chlorine/chloramine from tapwater), the waterchanges will sort things out.
Also, a 2ft tank may be a bit small for your two axies, you'll also find it fouls faster and warms up faster during the summer months.
