Patient received her MMR vaccine during her 1 year well visit on 3/24/2016 Manufacturer MERCK L033589 Until this time, she was on track with her milestones. Started crawling at 5 months, walking at the age of 10 months, had good appetite, overall was in good health with no concerns. She was saying simple 1 syllable words ?mama , dada?). Per pediatrician notes on the 12 months visit MD said ?well baby, no concerns, on track with her development?.  After receiving MMR vaccine on 3/24/2016 she became lethargic later that night and had a low grade fever of 101 (which was explained to us was ?normal?). She was still very tired and irritable the following day and had very poor appetite. These symptoms continued until the following week. And even though her fever resolved, her energy level was not the same.   My husband and I noticed that patient was not the same child anymore.  Her appetite became very poor, she didn?t make any progress in her vocabulary (at 15 months she was still saying 1 syllable words).  At out 18 months visit, pediatrician was concerned with poor appetite and sleep, along with bad temper tantrums. She also didn?t make much progress with her speech, her vocabulary only consisted of 4-10 words per her chart records. Per MD note ?patients has some behavioral issues?.   At 2 year follow up, she really was behind on her speech, still only used simple words and no sentences, and only gained 1 pound since 18 months follow up visit. She also developed GI symptoms, constipation, hard stools and her appetite didn?t improve since previous visit. Per pediatrician notes ?developmental and behavioral issues? were noted at that time. We had another follow up visit with Dr. on August 3rd, 2017 regarding patient?s very poor appetite and developmental delay issues. Per MD after visit summary ?growth and eating concerns, as well as speech concerns were noted?. At 2 years 6 months patient?s speech really didn?t progress, she only used simple words and rarely combined them into sentences, her articulation was quiet poor as well. So Dr. referred us to speech therapist for an evaluation. Per initial speech therapist evaluation, on 09/26/2017, patient had expressive language disorder and articulation disorder. Her expressive language skills were consistent with that of an 18 months old and receptive language skills of an 21 months old. Her vocabulary was reduced and she did not consistently combined words into phrases. She also demonstrated decreased oral motor range of motion when producing words. Per speech therapist summary, difficulties in these areas have negatively impacted patient?s ability to functionally communicate her needs and wants in her daily life. And speech therapy was initiated at twice a week sessions.  At the age of 3, patient was only able to use 3-4 words sentences with very poor articulation. We are still seeing therapist for speech therapy weekly. Patient is still behind in her development, she is 4.5 now, and even though her vocabulary and speech improved since our initial evaluation, she is still behind in articulation with speech equivalent of a 3 year old. Her appetite is still very poor and she still has a lot of behavioral concerns, as well  GI issues (constipation, recurring enemas and Miralax use daily). At this point, we saw GI specialist Dr. as well as nutritionist with very little improvement.