As the episode recedes, try some of the the exercise outlined in the Yoga Site's carpal tunnel article. They may help prevent a recurrence. Like carpal tunnel, tendonitis is caused by repetitive stress. Examine your work habits and see if there is a more ergonomic way to function. It's okay to continue practicing Yoga while you are pregnant as long as you were practicing before conception.
Yoga is a great way to keep fit during pregnancy.
In general, however, you want to avoid strain, compressing the belly or abdomen and inverted postures, especially in the later stages. Many public libraries also carry books about Yoga and pregnancy. It's also a good idea to work with a Yoga teacher with pre-natal Yoga experience. Migraines are caused by the sudden constriction and then dilation of blood vessels to the brain. No one knows what causes the blood vessels to behave this way.