The social structure and class changes in Sweden during the Middle Ages had many problems and was quite complicated.

1. Feudal System: There was a strict hierarchy called the feudal system. At the top were kings and nobles, followed by lower-level lords and then serfs. This system created a big gap between different social classes, which often led to anger from the lower classes.

2. Limited Mobility: People could not move between classes easily. Serfs were stuck working on the land, which kept them poor and unhappy.

3. Conflict and Strife: The nobles often fought for power, which caused problems and wars. Without a strong leader, there was chaos that affected everyone in the kingdom.

4. Economic Disparities: As trade grew, only a few people became wealthy. This made the differences between the rich and poor even larger, making life harder for peasants.

Possible Solutions:

• Land Reforms: Changing land ownership could help spread wealth and improve farming. This would benefit the lower classes.
• Strengthening Central Authority: A strong central government could take away some power from feudal lords and help create a fairer system.
• Social Programs: Investing in education and support services could give lower-class people the skills they need to improve their lives. This would help create a more balanced society.

By tackling these issues, there is a chance for a stronger and fairer Swedish society during the Middle Ages.