Bellingham, who scored one of the goals of the tournament with a stoppage-time overhead kick against Slovakia in the round of 16, said on Tuesday (Wednesday AEDT) he received unfair criticism for his performances.
"I've got to be honest, I think I lost my smile a lot after the Euros when it came to playing for England because I felt like I was a little bit mistreated in comparison to what I contributed," he said.
"I felt like some of it was a bit harsh on me. I felt I was a bit like the scapegoat. Maybe I was feeling a little bit sorry for myself."
Bellingham went to the Euros following a brilliant season with Madrid, where he won the Spanish league title and the Champions League.
He was also named player of the season in Spain's top division.
Bellingham scored two goals at the Euros as England finished runners-up after losing to Spain in the final.
"I felt like I contributed some pretty big moments and, in the end, it kind of felt like the whole world was crumbling down on me after the Euros, especially after the three days following the final. It wasn't a nice feeling," he said.
Bellingham has just helped England to promotion to the top tier of the UEFA Nations League and posted on Instagram this month that he had "got his smile back".
He is back in his homeland this week as Madrid face Liverpool in the Champions League on Wednesday (Thursday AEDT).
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