Need a Second Opinion on My Eating Habits

new here uh I'd like a second opinion about something I'm recently going through. so I recently moved back in with my father after breaking up with my girlfriend of 6 years that I've been living with for the past year, and the emotional journey from that so far hasn't been particularly difficult but the physical is a different story. since I moved back in with him my appetite has curbed almost completely and whenever I get hunger pains Id rather try to lay down and rest it out. my mental was I'd like to say on the better side of the transition but my eating habits are starting to have a rough impact on it. it's been about a month I moved in and I've already lost about 20 pounds and that's a lot for me because I only weigh around 135 to begin with and I already don't gain weight easily. do I have a developing eating disorder or am I just going through a phase of sorts?