Not a failure of faith

Do not be anxious about anything sounds like an instruction to stop feeling something. Read the whole sentence: it has a but in the middle. Anxiety is not forbidden here, it is redirected.

Read

Philippians 4:6–7KJV

Verse 6. Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God. Verse 7. And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus.

Read it in context

Think about this

Name the specific thing. Not the general weight of it, the one you would say if somebody asked.

Pray

God, this is what I am afraid of. I am telling you rather than carrying it.

These are words to start from, not words you have to use.

Continue in prayer

If you want to take one more step

If this is persistent or severe, speak to a doctor as well. Asking for help is not a lapse of faith.