What's wrong with my transmission?

Ok so I have a 2002 Honda Accord EX V6 and this morning I started noticing something wrong with my transmission because the D4 was flashing. Normally when I drive from a complete stop it shifts normally and shifts twice to get to about 42 mph. But today it shifted from 1st gear at a high RPM and when I tried to get it to shift into second gear it wouldn't shift to second. And normally when I'm driving at 55 mph and I put my car in cruise control the RPM stats at about 1600-1800RPM. But when I did it today it stayed at 3,000 RPM. I have an automatic transmission. Can anybody tell me what's wrong?

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