My 14 Month Old Developed A Lump In Her Cheek

My 14 month old developed a lump in her cheek under the skin I took her took the Dr they told me could be infection starting put a warm compress on it every couple hours and Tylenol every 4 hours for 48 hours. If it doesn't go away then go back and they will start antibiotics. It didn't get any worse my baby has no other symptoms it's a bit warm to touch sometimes. I brought her back to the Dr and he told me it's a bruise and not to worry. I'm not convinced. Why would one Dr say infection might be starting and the next say bruise?