unfortuantly that is life, people go about their day to day lives and forget about the others they pass on the way. its not fair and its not right and it hurts unbeleiably,but dont loose faith and dont judge Hashem and His thruthfelness on a few hundren people who are arent the smartest they are human,being frum is your love and trust in Hashem no matter what happens from Him or He sends to you through others. im sorry you are sick and i do hope you have a complete refuah physicaly and with your practice.
I know this isnt what you would want ot hear when hurting but,honestly think to yourself if it happend to another person you knew in the shul would you relaly noticed,have the number,know them to call? dont walk away bcause of the silence,learn how to better yourslef from it