I received a strange message saying that I didn't catch a cold.

There may be many possible explanations for this situation, depending on your communication style and communication style. Here are some possible explanations:

1. He may not know how to reply to your message or how to comfort you, so he chooses to say something unimportant to avoid embarrassment or make you feel uncomfortable.

2. He may think that your message is not very important, or that you are just coquetry or seeking attention, so he doesn't take your message seriously.

He may not care about your health, so he didn't respond as you expected.

He may be busy with other things and don't have enough time and energy to reply to your message.

In either case, the best solution is to communicate with him directly, tell him your feelings and expectations, and let him know your thoughts and needs. This will enable you to better understand each other, enhance mutual trust and communication, and thus establish a healthier and more stable relationship.