Overcoming Codeswitching Between L2 and L3

Greetings. So, I love language learning, and I have gotten my Russian up to a solid C1, after many years of work. Two months ago, I was easily having long conversations entirely in Russian.

I am also studying Spanish, and had a level of B1ish, but had very little opportunity to use it. Until December, when I spent 2 months in Puerto Rico and did intensive Spanish lessons. Now I can have B1/2 level conversations in Spanish, with some difficulty.

But now that my stay in PR is over, I really need to be able to switch back to Russian for work. And I am finding that when I talk to my Russian tutor, and especially with others, I am code switching random words. The Spanish is interfering massively with my Russian!

I don't have much interference with English, my native language--though sometimes a word in Spanish or Russian rises into my mind, I am able to actually vocalize the correct language.

Has this happened to you? Is there any good way to facilitate conversation without codeswitching?

In some ways, it was easier when my L3 was less strong.