"To feel" is the verb "sentir". Do not confuse this with "sentar", which means "to sit".
I believe it is Sientolo
sentir or siento
i feel young = me siento joven
"I feel tired" would be "Siento cansado"
Me siento como
Me siento terrible
me siento burlado
"Me siento mal."
Me siento ignorado
"No me siento bien."
Yo siento enfermo
Te sientes como un niño perdido would be the best way to say "You feel like a lost child" in Spanish.