The Flu really screwed my metabolism up and get back on track

I steadily lost my weight over two years and kept the 47 pounds off. The last year I was just maintaining my weight at 135. I got the flu in December and could barely eat for 4 days. I didnt have an appetite and even drinking made me feel sick. I would try to force myself to eat and drink because I knew I had to but I still couldnt manage much. The first day I could only eat 300 calories, then 500, then 800, and on the 4th day i was proud to get to 1000. During those 4 days I lost 3 lbs. By the 5th day I was back to normal and eating 1400-1600 from that point on ( my maintenance is 1620. when I exercise I eat more than that).

I dont care that I gained those 3 lbs back because it was not normal weight loss. I was sick. But not only did I gain back the 3 I lost, I gained an additional 3lbs ( 6 total) and I am in no way eating enough to gain weight. I should only maintain. I think my body got so screwed up from that flu that it thought it was starving and started storing calories/fat and I cant figure out how to get back on track. I am not shifting the weight and I am scared I will keep gaining. I tried to up my calories higher, then dropping them back to 1380 ( to lose a half pound a week ) but that didnt work. I started to add cardio but a foot and hand injury derailed me temporarily ( i should be able to resume that in 2 weeks).

Has getting sick ever threw a monkey wrench in your progress? How long to it take your body to get back to normal? Any suggestions on what I can do? 3 lbs doesnt seem like a problem to most people but with my body type those 3 lbs make my pants fit too tight in the waist and the next size up is just too baggy. So 3lbs on me is actually uncomfortable and makes a big difference when I cant seem to shift it.